1. Field of the Invention
The invention relates to a fiber bundle consisting of a plurality of optical fibers tied in a bundle, and an endoscope apparatus capable of photographing tomographic images of a object inside a living body or the like.
2. Description of the Prior Art
An endoscope system used for observing the interior of a patient""s body cavity has an endoscope to be inserted into the patient""s body cavity and an external unit connected to this endoscope. The external unit includes a light source section and a processor.
The endoscope has an elongate insertion cube to be inserted to the patient""s body cavity. The endoscope also has an illumination optical system, an objective optical system and a CCD. The illumination optical system, connected with the light source section in the external unit, illuminates an object (which is an inner wall of the body cavity) through an illuminating window provided at the distal end of the insertion tube. The objective optical system forms an image of the object through an observing window provided at the distal end of the insertion tube. The CCD is placed near an image-forming plane of the objective optical system, and connected to the processor in the external unit. Through the insertion tube is laid a forceps charnel which is opened at the distal end of the insertion tube. Through the forceps channel, a forceps or various operative instruments are guided to the distal end of the insertion tube from the proximal end thereof.
By using such an endoscope system, the operator can observe the interior of a patient""s body cavity. More specifically, the operator inserts the endoscope into the patient""s body cavity, and illuminates a inner wall of body cavity through the illumination optical system. Then, the objective optical system forms the image of the inner wall of the body cavity onto a pick-up plane of the CCD surface. The CCD converts this image into image signals, and transmits the same to the processor in the external unit. The processor in the external unit then processes the received image signals of the inner wall of the body cavity to display the picture of the inner wall onto a monitor. In this state, the operator observes the interior of the patient""s body cavity, displayed on the monitor.
If finding a location having the possibility of cancer or a tumor through this observation, the operator inserts a forceps or a biopsy needle into the body cavity through the forceps channel of the endoscope so as to excise tissue from the location. Thus excised tissue is objected to pathologic tests, and a diagnosis is given on the basis of the pathologic test results.
According to the conventional endoscope system of the above-described configuration, what is displayed as images is nothing but the surface of the inner wall of the patient""s body cavity. Therefore, biopsy is needed in order to know the condition of tissue under the surface of inner wall of the body cavity. In particular, biopsy is absolutely necessary for early detection of cancer, small tumors, and the like. Nevertheless, the pathologic tests on the tissue excised through the biopsy inevitably consume some time, resulting in a problem that the final diagnosis gets behind.
Moreover, with consideration given to the burden on the patient, the biopsy must be limited in area and in the number of times. Accordingly, simply administering pathologic tests not always promises an accurate diagnosis if lesions might also exist outside the operator-designated biopsy location.
An object of the present invention is to provide an endoscope apparatus which makes it possible to give an accurate diagnosis in a short time, and a fiber bundle which can be used in such endoscope apparatus.
A fiber bundle according to the present invention, having been devised to achieve the foregoing object has a plurality of first optical fibers and a plurality of second optical fibers. These two types of optical fibers are tied at their distal ends to form a composite bundle portion. The first optical fibers are tied at their proximal ends to form a first branched bundle portion. The second optical fibers are tied at their proximal ends to form a second branched bundle portion.
In the composite bundle portion, both the optical fibers may be tied so that respective distal ends of the first optical fibers and respective distal ends of the second optical fibers are alternately arranged into a checkered pattern to form a square close-packed array as a whole. Moreover, in the composite bundle portion, both the optical fibers may be tied so that each of the first optical fibers is surrounded with six of the second optical fibers to form a hexagonal close-packed array as a whole. Furthermore, in the composite bundle portion, both the optical fibers may be tied so that the first optical fibers are juxtaposed to each other and that the second optical fibers are arranged around the first optical fibers in a square close-packed array or hexagonal close-packed array.
In the first branched bundle portion, the first optical fibers may be arranged in either of a hexagonal close-packed array and a square close-packed array. Similarly, in the second branch bundle, the second optical fibers may be arranged in either of a hexagonal close-packed array and a square close-packed array.
An endoscope apparatus according to the present invention, having been devised to achieve the foregoing object has the fiber bundle described above, third optical fibers as many as the first optical fibers in the fiber bundle, an optical coupler, a low-coherent light source, an objective optical system, a reflecting member, an optical path length adjusting mechanism, a photodetector and a control section. The optical coupler optically couples each of the first optical fibers to corresponding one of third optical fibers. The low-coherent light source is arranged on the proximal ends of either the first optical fibers or the third optical fibers, so as to emit low-coherent light to be incident on the optical fibers. The objective optical system is opposed to the distal end of the composite bundle and individually converges low-coherent light beams emitted from the respective distal ends of the first optical fibers in the composite bundle portion and converges the respective low-coherent light beams reflected by an object to be incident on optical fibers as measurement light beams. The reflecting member is opposed to the respective distal ends of the third optical fibers and reflects low-coherent light beams emitted from those respective distal ends to be incident on the third optical fibers as reference light beams. The optical path length adjusting mechanism makes a relative change between the optical path length from the optical coupler to the object through the respective first optical fibers and the optical path length from the optical coupler to the reflecting member through the respective third optical fibers. The photodetector is arranged on the proximal ends of the other of the first optical fibers and the third optical fibers and detects interfered light beams caused by interferences between the measurement light beams and the reference light beams. The control section forms a tomographic image of the object on the basis of a signal detected by the photodetector while the optical path length adjusting mechanism makes the a relative change.
Here, the low-coherent light source may be a super-luminescent diode. This low-coherent light source may be arranged on the proximal end of the first optical fibers with the photodetector on the proximal end of the third optical fibers. Alternatively, the low-coherent light source may be arranged on the proximal end of the third optical fibers, with the photodetector on the proximal end of the first optical fibers.
The first optical fibers in the fiber bundle and the third optical fibers maybe a single-mode optical fiber, respectively. The individual first optical fibers in the fiber bundle, the individual third optical fibers, and the optical coupler may have the property of polarization.
The optical path length adjusting mechanism mentioned above may have the structure of moving the reflecting member so as to approach or recede from the distal ends of the third optical fibers to change the optical path length from the optical coupler to the reflecting member through the respective third optical fibers with respect to the optical path length from the optical coupler to the object through the respective first optical fibers. A piezo element may be used as the mechanism for driving the reflecting member. A voice coil motor, a servomotor, or the like may be used instead thereof.
The optical path length adjusting mechanism may change the optical path length from the optical coupler to the object through the first optical fibers with the reflecting member held stationary. The reflecting member may be a reference mirror, a corner cube, or the like.
Furthermore, the endoscope apparatus may be capable of ordinary observations and fluorescence observations through the second optical fibers in the fiber bundle.
The displaying section may include a CRT, a liquid crystal display, a plasma display, or the like.